Renee Zellweger admitted it was a "no brainer" signing up for 'Judy'.
The 50-year-old actress will portray the late Judy Garland in the upcoming biopic and when it was first pitched to her, she couldn't find any faults with the idea.
She said: "For as long as I can remember, Judy Garland has been someone who has always just been there - well, I'm sure for you as well as me.
"So when I was asked to be part of this movie about her life, it seemed to me to be a no-brainer.
"To be able to spend time exploring her, her life and her talent? What's not to love about a project like that?"
Renee found working on the movie a "very special" experience and it became like a "love letter" to the 'Wizard of Oz' star.
She told Britain's HELLO! magazine: "One thing I loved about making this movie was that making it didn't feel like, 'Bang! Here we go off to the races.'
"It felt like a very quiet exploration of who Judy was, a learning experience.
"Because everyone on the set had their own personal feelings about Judy, it didn't even feel like a traditional movie-making experience, more like this daily co-operative celebration of her and what she meant to everyone.
"I've never been part of something as special as that. It became like a love letter really."
'Judy' is set in 1968, during a time when the 'Wizard of Oz' actress headed to London in an effort to revive her career.
The movie sees the star perform sold-out shows at the Talk of the Town nightclub, and follows her as she reminisces with friends and fans and begins a whirlwind romance with musician Mickey, who she married three months before her death.
Judy passed away at the age of 47 in 1969 due to an accidental overdose, and the film also touches on her struggles with drug and alcohol issues.
The movie is based on the musical drama 'End of the Rainbow' by Peter Quilter, which was adapted into a script written by 'The Crown' scribe Tom Edge.